i just say
''hi sorry to bother you, can i intrest you in a quote for your window cleaning?''
short and sweet, dressed in full uniform ironed and smart
i get loads of compliments on how smart and proffesional i come across
be polite and confident, even if they say no i say ''thankyou for you time''
i had someone come after me after saying no, and then i got a job of them because i was so polite
works well for me
thanks colin